LCDI power cord system and method

ABSTRACT

A system and method for an LCDI power cord and associated circuits is provided. The system and method include energizing shielded neutral wires and shielded line wires and monitoring the energized shields for surges, e.g., arcing, detected by a Leakage Current Detection Circuit (LCDC) and/or voltage drops, e.g., shield breaks, detected by a Shield Integrity Circuit (SIC).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present continuation-in-part application is related to, claims theearliest available effective tiling date(s) from (e.g., claims earliestavailable priority dates for other than provisional patent applications;claims benefits under 35 USC § 119(e) for provisional patentapplications), and incorporates by reference in its entirety all subjectmatter of the following listed application(s) (the “RelatedApplications”) to the extent such subject matter is not inconsistentherewith; the present application also claims the earliest availableeffective filing date(s) from, and also incorporates by reference in itsentirety all subject matter of any and all parent, grandparent,great-grandparent, etc. applications of the Related Application(s) tothe extent such subject matter is not inconsistent herewith:

U.S. provisional patent application 63/013,742, entitled “LCDI ShieldContinuity Monitoring Circuits”, naming Victor V. Aromin as firstinventor, filed 22 Apr. 2020. And U.S. patent application Ser. No.16/935,895 which claims priority from U.S. provisional patentapplication 62/876,960, entitled “Power Cord”, naming Victor V. Arominas first inventor, filed 22 Jul. 2019; and U.S. provisional patentapplication 62/880,970, entitled “Power Cord”, naming Victor V. Arominas first inventor, filed 31 Jul. 2019.

BACKGROUND 1. Field of Use

This invention relates to a power cord. In particular, it relates to apower cord for an appliance that has a built-in leakage currentdetection and interruption (LCDI) conductor for detecting a leakagecurrent in the power cord.

2. Description of Prior Art (Background)

With the wide use of household electrical appliances, such as airconditioners, washing machines, refrigerators, etc., more attention isbeing paid to the safety of using such appliances. An appliancetypically has a power cord of one meter or longer. As shown in FIG. 1,such a power cord is made of three copper wires 11, 6 and 8 for carryingpower, three insulating layers (made of rubber or plastic) 10, 5, and 7surrounding the respective copper wires, two metal sheaths 19 and 14(made of thin copper wires woven together) surrounding two insulatinglayer, respectively, and an outer insulating layer 1 (made of rubber orplastic) enclosing the wires.

Such a power cord may age due to long-term use, or become damaged whenthe appliance is moved, which may cause a leakage between the phase lineand the neutral or ground lines in the cord. Such leakage current maycause sparks, which may cause fire and property damages. To quickly andaccurately detect leakage current in the power cord, an additionalconductor is provided and electrically connected to the metal sheath 19,14. Leakage current can be detected by detecting a voltage on the metalsheath. The metal sheaths are conventionally made by weaving thin copperwires. The cost of the power cord has increased due to the increase costof the copper material.

Another prior art solution is shown in FIG. 2. A power cord includesthree copper wires 11, 6 and 8 for carrying power and a leakage currentdetection conductor 3 for detecting a leakage current in the power cord.As before the three copper wires 11, 6 and 8 are surrounded by threeinsulating layers (made of rubber or plastic) 10, 5, and 7,respectively. Two insulating layers 10, 5 are surrounded by metalconductive layers 9, 4, respectively. The leakage current detectionconductor 3 is provided adjacent the two metal conductive layers 9, 4and is in contact with both of them. A metal sheath 2 encloses the threewires with their respective insulating layers and metal conductivelayers as well as the leakage current detection conductor 3. An outerinsulating layer 1 (made of rubber or plastic) is provided outside ofthe metal sheath 2.

The metal conductive layers 9, 4 may be made of a thin copper foil, tinfoil, aluminum foil, or conductive rubber. The leakage current detectionconductor 3 may be formed of one or more copper wires or aluminum wires.When leakage current is present between copper wires 11 and 6, 11 and 8,or 6 and 8, the leakage current detection conductor 3 can detect theleakage current via the metal conductive layers 9 or 4. As shown in FIG.2, this prior art solution requires another conductive sheath 2surrounding all the cables and the detection conductor 3.

BRIEF SUMMARY

Accordingly, the present invention provides a power cord useful forappliances such as air conditioners, washing machines, refrigerators,etc. which has a built-in leakage current detection conductor fordetecting a leakage current in the power cord.

In accordance with one embodiment of the present invention analternating current (AC) power cord is provided. The AC power cordincludes a neutral wire assembly, having an insulated conductive neutralwire and a conductive neutral wire shield surrounding the insulatedneutral wire insulator. The conductive neutral wire shield includes aconductive side and a non-conductive side and is wrapped around theinsulated neutral wire with the conductive side facing outwards. The ACpower cord includes a conductive flexible media wrapped around theconductive side of the neutral wire shield. The AC power cord alsoincludes a line wire, assembly, wherein the line wire assembly includesa conductive shield having a conductive side and a non-conductive sideand is wrapped around the insulated line wire with the conductive sidefacing inwards. The conductive neutral wire shield and the conductiveline wire shield are connected in series at one end of the AC powercord.

The invention is also directed towards an alternating current (AC) powercord having an insulated neutral wire, an insulated line wire, aninsulated return wire, and a ground wire. Also included is a conductiveshield surrounding the insulated neutral wire, the insulated line wire,the insulated return wire, and the ground wire. The conductive shieldincludes an outwardly facing conductive side and an inwardly facingnon-conductive side. A conductive flexible media surrounds theconductive side of the conductive shield. The conductive flexible mediaand the return wire are connected in series at one end of the powercord.

In accordance with another embodiment of the present invention an ACpower cord is presented. The AC power cord includes an insulted neutralwire surrounded by a conductive neutral wire shield having a conductiveside and a non-conductive side. The conductive side of the neutral wireshield faces outwards. Surrounding the neutral wire shield is aconductive flexible media. The AC power cord also includes an insultedline wire surrounded by a conductive line wire shield having aconductive side and a non-conductive side. The conductive side of theline wire shield faces outwards. Surrounding the line wire shield is asecond conductive flexible media. The conductive line wire shield andthe conductive neutral wire shield are connected in series at one end ofthe AC power cord.

In Accordance with another embodiment of the present invention LeakageCurrent Detection Interrupter (LCDI) circuit for interrupting AC powerfrom an AC source is provided. The LCDI circuit is electricallyconnectable to an insulated neutral wire surrounded by a neutral wireshield (NWS) and an insulated line wire surrounded by a line wire shield(LWS). The LCDI circuit also includes a power supply circuit forsupplying a rectified waveform and a floating load connected to thepower supply circuit. The floating load connected to the power supplycircuit includes a leakage current detection circuit (LCDC) fordetecting leakage current from the insulated neutral wire or theinsulated line wire and a shield integrity circuit (SIC) for monitoringthe NWS and LWS integrity.

The invention is also directed towards a method for constructing a powercord and circuit for detecting and interrupting line voltage between analternating current (AC) line end and a load end of the power cord upondetection of a power cord fault. The method includes providing aninsulated conductive neutral wire between the load end and AC line endof the power cord and wrapping the insulated conductive neutral wirewith a neutral wire shield having a conductive side of the neutral wireshield facing out. The method includes wrapping a conductive flexiblemedia around the conductive side of the neutral wire shield. The methodfurther includes providing and line wire shield having a conductive sideand a non-conductive side an insulated conductive line wire and wrappingthe line wire shield around a tinned wire and an insulated line wirewith the conducting side facing in and in electrical contact with thetinned wire. The method includes connecting the tinned wire to theconductive flexible media in series at the load end of the power cord.The method further includes interrupting line voltage if current betweenthe insulated line or insulated neutral wire and any one of the shieldsis detected; and/or includes interrupting line voltage if shieldintegrity is compromised or otherwise broken, such as, for example, abreak in a shield or corrosion. The method also includes providing arectifying power supply circuit for energizing the neutral wire shieldwith a voltage.

In accordance with another embodiment of the present invention a methodfor interrupting AC line voltage between an alternating current (AC)line end and a load end of a shielded power cord upon detection of apower cord fault is provided. The method includes providing a leakagecurrent detection circuit (LCDC) for detecting AC leakage current fromthe power cord and interrupting line voltage between the AC line end andthe load end of the shielded power cord if leakage current is detected.The method includes connecting the LCDC and SIC to the shielded powercord and providing a power supply circuit (PSC) for energizing the LCDC,SIC, and the shielded power cord with a voltage. Providing the LCDCfurther includes providing a bi-stable latching device having an on/offstate and a charge holding device connected to a controlling port of thebi-stable latching device; such as, for example, a transistor base or anSCR gate port. The method includes, during normal operation, chargingthe charge holding device to a charge less than the trigger chargeneeded to trigger the bi-stable latching device to its on-state, but ofsufficient charge to minimize the time needed to trigger the device if afault is detected and to minimize damaging inrush current. The methodfurther includes providing a shield integrity circuit (SIC) formonitoring shielded power cord integrity and interrupting line voltagebetween the AC line end and the load end of the shielded power cord ifshield integrity is compromised.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a cross-sectional view showing the structure of a conventionalpower cord;

FIG. 2 is a cross-sectional view showing the structure of anotherconventional power cord with a leakage current detection conductor;

FIG. 3 is a cut away side view showing the structure of a power cordwith leakage current detection conductors according to an alternateembodiment of the present invention;

FIG. 3A is a cross-sectional view showing the structure the power cordshown in FIG. 3;

FIG. 3B is a cut away side view showing the structure of a power cordwith leakage current detection conductors according to an alternateembodiment of the present invention;

FIG. 3C is a cross-sectional view showing the structure the power cordshown in FIG. 3B;

FIG. 3D is a cut away side view showing the structure of a power cordwith leakage current detection conductors according to an alternateembodiment of the present invention;

FIG. 3E is a cross-sectional view showing the structure the power cordshown in FIG. 3D;

FIG. 4 is a cut away side view showing the structure of a power cordwith leakage current detection conductors and an immersion detectioncable according to an embodiment of the present invention;

FIG. 4A is a cut away side view showing the structure of a power cordwith leakage current detection conductors and a twisted pair immersiondetection cable according to an embodiment of the present invention;

FIG. 5 is a circuit block diagram of a LCDI circuit connectable to thepower cords shown in FIG. 1, FIG. 2, FIG. 3, FIG. 3A-E;

FIG. 6 is a block diagram of a LCDI circuit connectable to the powercords shown in FIG. 4 or FIG. 4A;

FIG. 7 is a detailed schematic diagram of the block diagram shown inFIG. 5;

FIG. 8 is an alternate schematic diagram of the block diagram shown inFIG. 5;

FIG. 9 is a detailed schematic diagram of the block diagram shown inFIG. 5;

FIG. 10 is an alternate schematic diagram of the block diagram shown inFIG. 5;

FIG. 10A is an exploded partial view of a circuit connection of thereturn wire shown in FIGS. 3B-E;

FIG. 11A is a waveform diagram for the normal condition of the ShieldIntegrity Circuit (SIC) shown in FIG. 7 or FIG. 8;

FIG. 11B is a waveform diagram for the fault condition of the SIC shownin FIG. 7;

FIG. 11C is a waveform diagram for the fault condition of the SIC shownin FIG. 8;

FIG. 12A is a waveform diagram for the normal condition of the SIC shownin FIG. 9 or FIG. 10;

FIG. 12B is a waveform diagram for the fault condition of the SIC shownin FIG. 9;

FIG. 12C is a waveform diagram for the fault condition of the SIC shownin FIG. 10;

FIG. 13 illustrates a flow diagram of a method for constructing a powercord for detecting and interrupting line voltage between an AC line endand a load end of the power cord in accordance with the presentinvention;

FIG. 13A illustrates a flow diagram of an alternate method forconstructing a power cord for detecting and interrupting line voltagebetween an AC line end and a load end of the power cord in accordancewith the present invention;

FIG. 13B illustrates a flow diagram of a second alternate method forconstructing a power cord for detecting and interrupting line voltagebetween an AC line end and a load end of the power cord in accordancewith the present invention;

FIG. 14A is a waveform diagram for the normal condition of the LeakageCurrent Detection Circuit (LCDC) shown in FIG. 7 or FIG. 8; and

FIG. 14B is a waveform diagram for the normal condition of the LeakageCurrent Detection Circuit (LCDC) shown in FIG. 9 or FIG. 10.

DETAILED DESCRIPTION

The following brief definition of terms shall apply throughout theapplication:

The term “comprising” means including but not limited to, and should beinterpreted in the manner it is typically used in the patent context;

The phrases “in one embodiment,” “according to one embodiment,” and thelike generally mean that the particular feature, structure, orcharacteristic following the phrase may be included in at least oneembodiment of the present invention, and may be included in more thanone embodiment of the present invention (importantly, such phrases donot necessarily refer to the same embodiment);

If the specification describes something as “exemplary” or an “example,”it should be understood that refers to a non-exclusive example; and

If the specification states a component or feature “may,” “can,”“could,” “should,” “preferably,” “possibly,” “typically,” “optionally,”“for example,” or “might” (or other such language) be included or have acharacteristic, that particular component or feature is not required tobe included or to have the characteristic.

Referring now to FIG. 3 and FIG. 3A of the drawings, there is shown acut away side view showing the structure of a power cord 400 withleakage current detection conductors according to an alternateembodiment of the present invention. In this embodiment the power cord400 includes a neutral wire or cable 45, a line wire or cable 48, and aground wire 46. Each of the wire or cables is surrounded by an insulatorlayer 43, 49, and 492. In addition, the insulating layers 492 and 43 ofthe line wire 48 and the neutral wire 45, respectively, are eachsurrounded by a shield; a conductive medium, 41 and 42, respectively. Itis appreciated that the conductive medium 41, 42 has a conductive sideand a non-conductive or less conductive side. The conductive medium 41,42 may be an aluminum foil shielding comprising a thin layer of aluminumand mylar composite tape. The conductive side of conductive medium 41 isfacing inwards and the less, or non-conductive side of the conductivemedium is facing inwards. The conductive side of conductive medium 42 isfacing outwards.

Still referring to FIG. 3 and FIG. 3A power cord 400 also includes asolid tin copper wire 495 disposed between conductive medium 41 andinsulator 492. The conductive side of conductive medium 42 is surroundedby a conductive flexible media 44. The conductive flexible media 44 maybe any suitable conductive flexible media woven to cover 30% of thesurface area of the conductive side of conductive medium 42 per unitlength. At least one end of the conductive flexible media 44 may beconnected to an LCDI circuit 494. In addition, at least one end of thewire 495 may also be connected to the LCDI circuit 494. The conductiveflexible media may be any suitable conductive material such as, forexample: conductive coatings, tapes, ribbons, a braided copper flexiblemedia, or a conductive flexible media woven from conductive materialsuch as, but not limited to, high-performance carbon fiber/gold/coppercomposite wire, conductive graphene wire, or conductive graphene yarn.

It is understood that any if insulators 492 or 43 become defective andcurrent leaks to the conductive side of conductive medium 41 or 42 thecurrent flows through conductive flexible media 44 or wire 495 where itis detected by LCDI circuit 494 and interrupt power between a linesource and load.

Referring also to FIG. 3B and FIG. 3C of the drawings, there is shown acut away side view showing the structure of a power cord 3B400 withleakage current detection conductors according to an alternateembodiment of the present invention. In this embodiment the power cord3B400 includes a neutral wire or cable 45, a line wire or cable 48,ground wire 46 and a return wire 3B01. Each of the wire or cables issurrounded by an insulator layer 43, 49, 492 (as shown in FIG. 3A) and3B49. The insulated wires 45, 46, 48 and 3B01 are surrounded wrapped bya shield; i.e., a conductive medium, 3B42. It is appreciated that theconductive medium 3B42 has a conductive side and a non-conductive orless conductive side. The conductive medium 3B42 may be an aluminum foilshielding comprising a thin layer of aluminum and mylar composite tape.The conductive side of conductive medium 3B42 is facing outwards and theless, or non-conductive side of the conductive medium is facing inwardstowards the center of power cord 3B400.

Still referring to FIG. 3B and FIG. 3C, the conductive side of theconductive medium 3B42 is surrounded by a conductive flexible media3B44. The conductive flexible media 3B44 may be any suitable conductiveflexible media woven to cover 30% of the surface area of the conductiveside of the conductive medium 3B42 per unit length. At least one end ofthe conductive flexible media 44 may be connected to an LCDI circuit3B494. In addition, at least one end of the return wire 3B01 may also beconnected to the LCDI circuit 3B494. The conductive flexible media maybe any suitable conductive material such as a copper flexible media, ora conductive flexible media woven from conductive material such as, butnot limited to, high-performance carbon fiber/gold/copper compositewire, conductive graphene wire, or conductive graphene yarn.

Referring also to FIG. 3D and FIG. 3E of the drawings, there is shown acut away side view showing the structure of a power cord 3C400 withleakage current detection conductors according to an alternateembodiment of the present invention. In this embodiment the power cord3C400 includes a neutral wire or cable 45, a line wire or cable 48,ground wire 46 and a return wire 3B01. Each of the wire or cables issurrounded by an insulator layer 43, 49, and 492. In addition, theinsulating layers 492 and 43 of the line wire 48 and the neutral wire45, respectively, are each surrounded by a shield, a conductive medium,3C42 and 3C42A, respectively. It is appreciated that each of theconductive mediums 3C42 and 3C42A has a conductive side and anon-conductive or less conductive side. The conductive medium 3C42 and3C42A may be an aluminum foil shielding comprising a thin layer ofaluminum and mylar composite tape. The conductive side of each of theconductive mediums 3C42 and 3C42A is facing outwards.

Still referring to FIG. 3D and FIG. 3E the conductive side of theconductive mediums 3C42 and 3C42A is surrounded or wrapped by conductiveflexible medias 3C44 and 3C44A. The conductive flexible medias 3C44 and3C44A may be any suitable conductive flexible media woven to cover 30%of the surface area of the conductive side of the conductive mediums3C42 and 3C42A 2 per unit length. At least one end of the conductiveflexible medias 3C44 and 3C44A may be connected to an LCDI circuit3D494. In addition, at least one end of the return wire 3B01 may also beconnected to the LCDI circuit 3D494. The conductive flexible medias 3C44and 3C44A may be any suitable conductive material such as a copperflexible media, or a conductive flexible media woven from conductivematerial such as, but not limited to, high-performance carbonfiber/gold/copper composite wire, conductive graphene wire, orconductive graphene yarn.

Referring also to FIG. 4 there is shown a cut away side view showing thestructure of a power cord 401 with leakage current detection conductorsas described earlier and an immersion detection cable 407 comprising aconducting wire 405 surrounded by an absorbent covering 406. Theimmersion detection cable 407 is arranged within the power cord 401 tobe in close contact with conductive flexible media 44 and/or conductivemedium 42. In this embodiment, moisture absorbed by the absorbentcovering 406 completes an electrical connection between conducting wire405 and conductive flexible media 44 and/or conductive medium 42. As isdescribed in more detail herein, the LCDI circuit 494A detects theelectrical connection between conducting wire 405 and conductiveflexible media 44 and/or conductive medium 42 and interrupt powerbetween a line source and load.

Referring also to FIG. 4A there is shown a cut away side view showingthe structure of a power cord 401A with leakage current detectionconductors as described earlier and a twisted pair immersion detectioncable 407A according to an embodiment of the present invention. Thetwisted pair immersion detection cable 407A includes conducting wires405A and 405B, each surrounded by an absorbent covering 406A and 406B,respectively. In this embodiment, moisture absorbed by the absorbentcovering 406A and 406B completes an electrical connection betweenconducting wires 405A and 405B and/or between conducting wires 405A or405B and conductive flexible media 44 and/or conductive medium 42 andinterrupt power between a line source and load. As is described in moredetail herein, the LCDI circuit 494 detects the electrical connectionand interrupt power between line source and load.

Referring also to FIG. 5 there is shown a circuit block diagram of aLCDI circuit 50 connectable to the power cords shown in FIG. 1, FIG. 2,FIG. 3, or FIG. 3A. LCD circuit 50 includes line shield 513, neutralshield 515, switch 518, power supply circuit 512, leakage currentdetection circuit (LCDC) 516, solenoid 519, and shield integrity circuit(SIC) 514. As shown herein the LCDE 516 and the SIC 514 comprise afloating load with respect to the power supply 512. SIC 514 includes SICcontroller 514A and SIC switch 514B. LCDC 516 includes LCDC switch 517A.Shield 515 is constructed and provided in accordance with any of theshields described earlier. As is described in more detail herein, whenmanual reset switch 518 is set line voltage is connected to LOAD and topower supply circuit 512 via solenoid 519. Power supply circuit 512supplies bias voltages to LCDC 517, SIC 514, and shields 513 and 515.Shields 513 and 515, having load ends, 513A and 515A, respectively, areconnected in series at their load ends. Power supply 512 is connected toshield 513 at its source end 513B; and, LCDC 517 and SIC 514 areconnected to shield 515 at its source or line end 515B. As is discussedand shown in more detail herein, the SIC 514 allows a small amount ofsolenoid current to flow through solenoid 519 but less than theenergizing current needed to energize solenoid 519 to disengage manualreset switch 518. It is appreciated that not starting from zeroenergizing current allows solenoid 519 to energize faster when a faultis detected.

Referring also to FIG. 6 there is shown a block diagram of a LCDIcircuit 60 connectable to the power cords shown in FIG. 4 or FIG. 4A. Itis well known that two dissimilar metals in electrical contact, such asconductive flexible media 44 and conductive layer 42, in the presence ofan electrolyte, such as water, begins to galvanically corrode. Thus, IDC66, connected to SIC 514 causes AC line power to be disconnected fromthe load if moisture is detected by IDC 66. Immersion detection cable(IDC) 66 can be either the immersion detection cable 407 or the twistedpair immersion detection cable 407A described earlier.

Still referring to FIG. 6, LCDI circuit 60 also includes light detectioncircuit (LDC) 64 connected to SIC 514. In the presence of lightimpinging on circuit 60, implying that circuit 60 is exposed to theelements, SIC 514 causes AC line power to be disconnected from the loadif light is detected by LCD 64.

Referring also to FIG. 7 there is shown a detailed circuit 70 of theblock diagram 50 shown in FIG. 5. LCDI circuit 70 includes line shield513, neutral shield 515, switch 518, power supply circuit 712, leakagecurrent detection circuit (LCDC) 716, solenoid 519, and shield integritycircuit (SIC) 714. Shield 515 includes conductive layer 42 surrounded byconductive flexible media 44 described earlier. As is described in moredetail herein, when manual reset switch 518 is set line voltage isconnected to LOAD and to power supply circuit 712 via solenoid 519.Power supply circuit 712 supplies bias voltages to LCDC 717, SIC 714,and shields 513 and 515. As is discussed and shown in more detailherein, the SIC 714 allows a small amount of solenoid current to flowthrough solenoid 519 but less than the energizing current needed toenergize solenoid 519 to disengage manual reset switch 518. It isappreciated that not starting from zero energizing current allowssolenoid 519 to energize faster when a fault is detected.

Still referring to FIG. 7 and FIGS. 11A-11B. When switch 518 ismechanically (manually) engaged AC line voltage is connect to LOAD. 60Hz AC line voltage is also connected to power supply circuit 712 viasolenoid 519. Power supply circuit 712, comprising bridge rectifier(diodes D1-D4) outputs a rectified unsmoothed DC signal at A. Therectified unsmoothed DC signal at A is routed through R6 to LCDC 717 andSIC 714, via shields 513 and 515 connected in series.

R6 drops the amplitude of rectified unsmoothed DC signal at A to apredetermined amplitude at B. Voltage dividers R3/R7 drops the amplitudeof rectified unsmoothed DC signal at B to a predetermined amplitude atC. Under normal conditions, the voltage amplitude at C, the gate of SCR2LCDC switch 517A, is insufficient to trigger SCR2 into an on condition.It will be appreciated, however, that C3 charges to a voltage determinedby R3, R7 to maintain a minimum voltage on the gate of SCR2. (See FIG.14A for full wave rectification and FIG. 14B for half waverectification.) If an adverse leakage condition occurs, e.g., arcingfrom AC line voltage to either shield 513 or 515, the gate voltage at Crises from the charge on C3 to trigger SCR2 into an on-condition. In theSCR2 on, or conducting condition, current flow through solenoid 519 isincreased to a solenoid energizing level to disengage manual resetswitch 518 and interrupt power between AC line source and load. Again,it is appreciated that not starting from zero gate voltage allows SCR2to trigger faster when a fault is detected than if the gate voltage wasstarting from zero volts. It is also understood that inrush current canexceed the current carrying capability of board connectors as well asPCB traces, resulting in damaging the connectors and traces. Thus,maintaining a minimum C3 charge minimizes inrush current and potentialcircuit damage in the event of an arcing condition.

Still referring to FIG. 7, the rectified unsmoothed DC signal at B isrouted to the base of npn transistor Q1, SIC controller 514A, via R2(see FIG. 11A), biasing Q1 into an on condition during the positivecycle of the rectified unsmoothed DC. When Q1(B) voltage drops belowV_(BE) Q1 turns off and the voltage at Q1(C), SIC switch 514B, is near 0v due to the unsmoothed DC signal at A dropping to near 0 v in thecycle. When the unsmoothed DC signal at A swings positive, Q1 is againbiased on, dropping the unsmoothed DC signal at A across R8, keeping Q2in an off condition during normal operation.

Still referring to FIG. 7, it is understood that under normal conditionsthe rectified unsmoothed DC signal at A is dropped across resistor R8and that R8 is sized to allow an amount of AC current less than the SOL1519 energizing current to flow through R8 through Q1 back to neutralwhen Q1 is conducting. During Q1's off state, or non-conducting state,SOL1 519 inductively opposes the change in current until Q1 again turnson, thus maintaining, or nearly maintaining the current flow throughSOL1 519. It is understood and appreciated that the small amount ofsolenoid current flowing through solenoid SOL1 519 is less than theenergizing current needed to energize solenoid 519 to disengage manualreset switch 518. It is further appreciated that not starting from zeroenergizing current allows solenoid 519 to energize faster when a faultis detected.

Still referring to FIG. 7, when shield integrity is compromised, suchas, for example, a break in shields 513, 515, or a voltage drop acrossareas of corrosion within the power cable, the bias-on voltage V_(BE) atthe base of Q1 is insufficient to keep Q1 in its conductive state. (SeeFIG. 11B.) The voltage at the base of Q2 (Q1C) rises to Q2's bias-onvoltage turning on Q2, sufficiently increasing current flow throughsolenoid 519 to energize solenoid 519 to disengage manual reset switch518. Thus, interrupting power from the AC line source to the load. It isunderstood and appreciated that the full wave bridge rectifier 712enables the SIC to detect and disconnect the AC line source from theload when a fault is detected during the positive or negative cycle ofan input AC waveform (not shown). In other words, the SIC detects andinterrupt power between the AC line source and load within 1 ms or lessfor a 60 Hz AC source.

Referring also to FIG. 8 is an alternate circuit diagram of the SICblock diagram shown in FIG. 5. The rectified unsmoothed DC signal at Bis routed to the base of npn transistor Q1 via R2 biasing Q1 into an oncondition, which in turn, drops rectified unsmoothed DC signal at Aacross R8. Thus, the gate voltage at the gate of SCR1 is insufficient totrigger SCR1. It is appreciated that the frequency of the rectifiedunsmoothed DC signal at the base of Q1 is of a sufficient frequency tokeep Q1 in a mostly conductive state in normal operations thusinhibiting sufficient bias-on gate voltage at the gate of SCR1. In otherwords, for example, when the rectified unsmoothed DC voltage signal atthe base of Q1 drops below the Q1 bias-on voltage, turning Q1 off, thebias-on gate voltage at the gate of SCR1 begins to rise. However, undernormal conditions, before there is sufficient bias-on gate voltage atthe gate of SCR1, Q1 turns back on, again dropping the gate voltage atthe gate of SCR1 below sufficient bias-on voltage (see FIG. 11A).

When Q1 V_(BE) voltage drops, i.e., due to fault such as, for example, abreak in shields 513, 515, or a voltage drop across areas of corrosion,the bias-on voltage at the base of Q1 is insufficient to keep Q1 in itsconductive state during the positive voltage swing a A. The gate voltageat the gate of SCR1 rises to SCR's gate bias-on voltage triggering SCR1(see FIG. 11C) which sufficiently increases current flow throughsolenoid 519 to energize solenoid 519 to disengage manual reset switch518. Thus, interrupting power from the AC line source to the load.

Referring also to FIG. 9 there is shown an alternate detailed circuit 90of the block diagram 50 shown in FIG. 5. LCDI circuit 90 includes lineshield 513, neutral shield 515, switch 518, power supply circuit 912,leakage current detection circuit (LCDC) 917, solenoid 519, and shieldintegrity circuit (SIC) 914. As is described in more detail herein, whenmanual reset switch 518 is set line voltage is connected to LOAD and topower supply circuit 912 via solenoid 519. Power supply circuit 912supplies bias voltages to LCDC 917, SIC 914, and shields 513 and 515. Asis discussed and shown in more detail herein, the SIC 914 allows a smallamount of solenoid current to flow through solenoid 519 but less thanthe energizing current needed to energize solenoid 519 to disengagemanual reset switch 518. It is appreciated that not starting from zeroenergizing current allows solenoid 519 to energize faster when a faultis detected.

Still referring to FIG. 9 and FIGS. 12A-12B. When switch 518 ismechanically (manually) engaged AC line voltage is connect to LOAD. 60Hz AC line voltage is also connected to power supply circuit 912 viasolenoid 519. Power supply circuit 912, comprising half wave rectifier(diodes D1-D2) outputs a half wave rectified unsmoothed DC signal at A.The rectified unsmoothed DC signal at A is routed through R6 to LCDC 917and SIC 914, via shields 513 and 515 connected in series.

R6 drops the amplitude of rectified unsmoothed DC signal at A to apredetermined amplitude at B. Voltage dividers R3/R7 drops the amplitudeof rectified unsmoothed DC signal at B to a predetermined amplitude atC. Under normal conditions, the voltage amplitude at C, the gate of SCR2LCDC switch 517A, is insufficient to trigger SCR2 into an on condition.It will be appreciated, however, that C3 charges to a voltage determinedby R3, R7 to maintain a minimum voltage on the gate of SCR2. If anadverse leakage condition occurs, e.g., arcing from AC line voltage toeither shield 513 or 515, the gate voltage at C rises from the charge onC3 to trigger SCR2 into an on-condition. In the SCR2 on, or conductingcondition, current flow through solenoid 519 is increased to a solenoidenergizing level to disengage manual reset switch 518 and interruptpower between AC line source and load. Again, it is appreciated that notstarting from zero gate voltage allows SCR2 to trigger faster when afault is detected than if the gate voltage was starting from zero volts.

Still referring to FIG. 9, the half wave rectified unsmoothed DC signalat B is routed to the base of npn transistor Q1, via R2 (see FIG. 1A),biasing Q into an on condition during the positive cycle of therectified unsmoothed signal. When Q1(B) voltage drops below V_(BE) Q1turns off and the voltage at Q1(C), is near 0 v due to the unsmoothedsignal at A dropping to near 0 v in the cycle. When the unsmoothed DCsignal at A swings positive, Q1 is again biased on, dropping theunsmoothed DC signal at A across R8, keeping Q2 in an off conditionduring normal operation.

Still referring to FIG. 9, it is understood that under normal conditionsthe rectified unsmoothed signal at A is dropped across resistor R8 andthat R8 is sized to allow an amount of AC current less than the SOL1 519energizing current to flow through R8 through Q1 back to neutral when Q1is conducting. During Q1's off state, or non-conducting state, SOL1 519inductively opposes the change in current until Q1 again turns on, thusmaintaining, or nearly maintaining the current flow through SOL1 519. Itis understood and appreciated that the small amount of solenoid currentflowing through solenoid SOL1 519 is less than the energizing currentneeded to energize solenoid 519 to disengage manual reset switch 518. Itis further appreciated that not starting from zero energizing currentallows solenoid 519 to energize faster when a fault is detected.

Still referring to FIG. 9, when shield integrity is compromised, suchas, for example, a break in shields 513, 515, or a voltage drop acrossareas of corrosion within the power cable, the bias-on voltage Vat atthe base of Q1 is insufficient to keep Q in its conductive state. (SeeFIG. 12B.) The voltage at the base of Q2 (Q1C) rises to Q2's bias-onvoltage turning on Q2, sufficiently increasing current flow throughsolenoid 519 to energize solenoid 519 to disengage manual reset switch518. Thus, interrupting power from the AC line source to the load.

Referring also to FIG. 10 is an alternate circuit diagram of the SICblock diagram shown in FIG. 5. The half wave rectified unsmoothed DCsignal at B is routed to the base of npn transistor Q1 via R2 biasing Qinto an on condition, which in turn, drops rectified unsmoothed DCsignal at A across R8. Thus, the gate voltage at the gate of SCR1 isinsufficient to trigger SCR1. It is appreciated that the frequency ofthe half wave rectified unsmoothed DC signal at the base of Q1 is of asufficient frequency to keep Q1 in a mostly conductive state in normaloperations thus inhibiting sufficient bias-on gate voltage at the gateof SCR. In other words, for example, when the rectified unsmoothed DCvoltage signal at the base of Q1 drops below the Q1 bias-on voltage,turning Q1 off, the bias-on gate voltage at the gate of SCR1 begins torise. However, under normal conditions, before there is sufficientbias-on gate voltage at the gate of SCR1, Q1 turns back on, againdropping the gate voltage at the gate of SCR1 below sufficient bias-onvoltage (see FIG. 12A).

When Q1 V_(BE) voltage drops, i.e., due to fault such as, for example, abreak in shields 513, 515, or a voltage drop across areas of corrosion,the bias-on voltage at the base of Q1 is insufficient to keep Q1 in itsconductive state during the positive voltage swing a A. The gate voltageat the gate of SCR1 rises to SCR1's gate bias-on voltage triggering SCR1(see FIG. 12C) which sufficiently increases current flow throughsolenoid 519 to energize solenoid 519 to disengage manual reset switch518. Thus, interrupting power from the AC line source to the load.

Referring also to FIG. 10A there is shown an exploded partial view of acircuit connection of the return wire shown in FIGS. 3B-E. Those skilledin the art will appreciate the alternate shield connections to circuitsdescribed earlier.

Referring also to FIG. 13 there is shown a flow diagram illustration ofa method for constructing a power cord for detecting and interruptingline voltage between an AC line end and a load end of the power cord inaccordance with the present invention 1300.

Step 1301 provides a unit length of an insulated conductive neutralwire. Step 1302 wraps the insulated neutral wire with a conductivewrapping having a conductive side and a non-conductive side, with theconductive side facing out. The conductive side of the wrapping may beany suitable conductive material such as, for example, aluminum foil.Step 1303 wraps a conductive flexible media around the wrapped neutralwire such that the flexible media is in electrical contact with theconductive side of the conductive wrap and covers 30% of the unit lengthof the wrapped neutral wire. The conductive flexible media may be anysuitable conductive material such as a copper flexible media, or aconductive flexible media woven from conductive material such as, butnot limited to, high-performance carbon fiber/gold/copper compositewire, conductive graphene wire, or conductive graphene yarn.

Step 1304 provides a unit length insulated conductive line wire and step1305 provides a unit length tinned conductive wire. The tinned wire maybe any suitable conductive wire such as a solid conductive wire orstranded conductive wire. Step 1306 wraps the tinned wire and theinsulated conductive line wire with a line wire shield having aconductive and non-conductive side with the conductive side facing inand in electrical contact with the tinned wire. (See FIGS. 3A-3B)

Step 1307 connects the tinned wire to the conductive flexible media orneutral shield at the load end of the power cord.

Step 1308 provides a leakage current detection circuit (LCDC) fordetecting leakage current from the conductive neutral wire or theconductive line wire and a shield integrity circuit (SIC) for monitoringthe neutral wire shield or the line wire shield integrity. The LCDC andSIC may be any of the embodiments previously described.

Step 1309 connects the LCDC and SIC to the conductive flexible media atthe line end of the neutral shield conductor. It is understood that theshields described herein are connected in series at the load end of thepower cord. Step 1310 provides a power supply circuit for energizing theLCDC and SIC and also energizes the line wire shield at the line end ofthe line wire shield with a first voltage.

Step 1313 interrupts AC line voltage if the LCDC detects a voltage(e.g., an arcing condition) rising above the first voltage.

Step 1314 interrupts AC line voltage if the SIC detects the firstvoltage falling below a second predetermined level. (See FIGS. 11A-12C).

Referring also to FIG. 13A there is shown an illustration of a flowdiagram of an alternate method for constructing a power cord fordetecting and interrupting line voltage between an AC line end and aload end of the power cord in accordance with the present invention,step 1301A.

Step 1302A provides a unit length insulated conductive: neutral wire,line wire, return wire, and ground wire. Step 1303A wraps the insulatedconductive: neutral wire, line wire, return wire, and ground wires witha shield having a conductive side and a non-conductive side with theconductive side of the shield facing out. (See FIGS. 3B-3C) Theconductive side of the wrapping may be any suitable conductive materialsuch as, for example, aluminum foil.

Step 1304A wraps a conductive flexible media around the shield such thatthe conductive flexible media is in electrical contact with theconductive side of the shield and the conductive flexible media covers30% of the unit length. The conductive flexible media may be anysuitable conductive material such as a copper flexible media, or aconductive flexible media woven from conductive material such as, butnot limited to, high-performance carbon fiber/gold/copper compositewire, conductive graphene wire, or conductive graphene yarn.

Step 1305A connects the return wire to the conductive flexible mediaand/or the shield at the load end of the power cord.

Steps 1306A and 1307A provides a leakage current detection circuit(LCDC) for detecting leakage current from the conductive neutral wire orthe conductive line wire; and a shield integrity circuit (SIC) formonitoring the neutral wire shield or the line wire shield integrity.The LCDC and the SIC are connected to the return wire. The LCDC and SICmay be any of the embodiments previously described.

Step 1308A provides a leakage current detection circuit (LCDC) fordetecting leakage current from the conductive neutral wire or theconductive line wire and a shield integrity circuit (SIC) for monitoringthe neutral wire shield or the line wire shield integrity. The LCDC andSIC may be any of the embodiments previously described.

Step 1309A connects the LCDC and SIC to the conductive flexible mediavia the return wire. It is understood that the shields described hereinare connected in series at the load end of the power cord.

Step 1310A provides a power supply circuit for energizing the LCDC andSIC and also energizes the line wire shield at the line end of the linewire shield with a first voltage.

Step 1313A interrupts AC line voltage if the LCDC detects a voltage(e.g., an arcing condition) rising above the first voltage.

Step 1314A interrupts AC line voltage if the SIC detects the firstvoltage falling below a second predetermined level. (See FIGS. 11A-12C).

Referring also to FIG. 13B there is shown an illustration of a flowdiagram of a second alternate method for constructing a power cord fordetecting and interrupting line voltage between an AC line end and aload end of the power cord in accordance with the present invention,step 13C00.

Step 13C01 provides a unit length insulated conductive neutral wire.Step 13C02 wraps the insulated conductive neutral wire with a neutralwire shield having a conductive side and a non-conductive side, with theconductive side facing out. Step 13C03 wraps a conductive flexible mediaaround the neutral wire shield such that the conductive flexible mediais in electrical contact with the conductive side of the neutral wireshield and the conductive flexible media covers 30% of the unit length.The conductive flexible media may be any suitable conductive materialsuch as a copper flexible media, or a conductive flexible media wovenfrom conductive material such as, but not limited to, high-performancecarbon fiber/gold/copper composite wire, conductive graphene wire, orconductive graphene yarn.

Steps 13C04 through 13C06 provide a unit length insulated conductiveline wire. The insulated conductive line wire is wrapped with a neutralwire shield having a conductive side and a non-conductive side, with theconductive side facing out. A conductive flexible media is wrappedaround the line wire shield such that the conductive flexible media isin electrical contact with the conductive side of the line wire shieldand the conductive flexible media covers 30% of the unit length. Theconductive flexible media may be any suitable conductive material suchas a copper flexible media, or a conductive flexible media woven fromconductive material such as, but not limited to, high-performance carbonfiber/gold/copper composite wire, conductive graphene wire, orconductive graphene yarn. (See FIGS. 3D-3E)

Step 13C07 connects a return wire to the line wire shield and theneutral wire shield at the load end of the power cord. Steps 13C08 and13C09 provide a leakage current detection circuit (LCDC) for detectingleakage current from the conductive neutral wire or the conductive linewire and a shield integrity circuit (SIC) for monitoring the neutralwire shield or the line wire shield integrity. The LCDC and SIC areconnected to the return wire.

Step 13C10 provides a power supply circuit for energizing the LCDC andSIC and also energizes the line wire shield at the line end of the linewire shield with a first voltage. Step 13C13 interrupts AC line voltageif the LCDC detects a voltage (e.g., an arcing condition) rising abovethe first voltage. Step 13C14 interrupts AC line voltage if the SICdetects the first voltage falling below a second predetermined level.(See FIGS. 11A-12C).

It should be understood that the foregoing description is onlyillustrative of the invention. Thus, various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the invention. For example, solid state devices SCR1 orQ2 can be any suitable solid-state device. Accordingly, the presentinvention is intended to embrace all such alternatives, modificationsand variances that fall within the scope of the appended claims.

What is claimed is:
 1. A method for constructing a power cord andcircuit for detecting and interrupting line voltage between analternating current (AC) line end and a load end of the power cord upondetection of a power cord atilt, the method comprising: providing aninsulated conductive neutral wire between the load end and AC line endof the power cord; providing a neutral wire shield having a conductiveside and a non-conductive side; wrapping the insulated conductiveneutral wire with the neutral wire shield with the conductive sidefacing out; wrapping a conductive flexible media around the neutral wireshield; providing an insulated conductive line wire between the load endand line end of the power cord; providing a tinned wire; providing aline wire shield having a conductive side and a non-conductive side;wrapping the insulated conductive line wire and the tinned wire with theline wire shield with the conductive side facing in and in contact withthe tinned wire; and connecting the tinned wire to the conductiveflexible media at the load end of the power cord.
 2. The method as inclaim 1 wherein wrapping a conductive flexible media around the neutralwire shield further comprises wrapping a copper flexible mediacomprising a 30% copper flexible media coverage per unit length of thepower cord.
 3. The method as in claim 1 wherein wrapping a conductiveflexible media around the neutral wire shield further comprises wrappinga conductive flexible media selected from the group consisting ofhigh-performance carbon fiber/gold/copper composite wire, conductivegraphene wire, and conductive graphene yarn.
 4. The method as in claim 1further comprises providing an immersion detection wire adjacent to theconductive flexible media between the load end and the line end of thepower cord.
 5. The method as in claim 1 further comprises providing atwisted pair immersion detection cable between the load end and the lineend of the power cord.
 6. The method as in claim 1 further comprising:providing a leakage current detection circuit (LCDC) for detecting ACleakage current from the conductive neutral wire or the conductive linewire; providing a shield integrity circuit (SIC) for monitoring theneutral wire shield or the line wire shield integrity; connecting theLCDC and SIC to the conductive flexible media at the line end of thepower cord; and providing a rectifying power supply circuit forenergizing the LCDC, SIC, and the tinned wire with a first voltage. 7.The method as in claim 6 wherein providing a shield integrity circuit(SIC) for monitoring the neutral wire shield or the line wire shieldintegrity further comprises interrupting line voltage between the loadend and the AC line end of the power cord if the first voltage fallsbelow a first predetermined level.
 8. The method as in claim 6 whereinproviding a leakage current detection circuit (LCDC) for detectingleakage current from the conductive neutral wire or the conductive linewire further comprises interrupting line voltage between the load endand the line end of the power cord if the first voltage exceeds a secondpredetermined level.
 9. A method for constructing a power cord having aload end and an AC line end, the method comprising: providing aninsulated conductive neutral wire between the load end and AC line endof the power cord; providing a neutral wire shield having a conductiveside and a non-conductive side; wrapping the insulated conductiveneutral wire with the neutral wire shield with the conductive sidefacing out; wrapping a conductive flexible media around the neutral wireshield; providing an insulated conductive line wire between the load endand line end of the power cord; providing a line wire shield having aconductive side and a non-conductive side; wrapping the insulatedconductive line wire with the line wire shield with the conductive sidefacing in; and connecting the neutral wire shield and the line wireshield in series at the load end.
 10. The method as in claim 9 whereinwrapping a conductive flexible media around the neutral wire shieldfurther comprises wrapping a copper flexible media comprising a 30%copper flexible media coverage per unit length of the power cord. 11.The method as in claim 9 further comprising: providing a leakage currentdetection circuit (LCDC) for detecting leakage current from theconductive neutral wire or the conductive line wire; providing a shieldintegrity circuit (SIC) for monitoring the neutral wire shield or theline wire shield integrity; connecting the LCDC and SIC to theconductive flexible media at the line end of the power cord; providing apower supply circuit for energizing the LCDC, SIC, and the line wireshield with a first voltage; and the SIC interrupting line voltagebetween the load end and the AC line end of the power cord if the firstvoltage falls below a first predetermined level.
 12. The method as inclaim 11 wherein providing a leakage current detection circuit (LCDC)for detecting AC leakage current from the conductive neutral wire or theconductive line wire further comprises the LCDC interrupting linevoltage between the load end and the AC line end of the power cord ifthe first voltage exceeds a second predetermined level.
 13. The methodas in claim 11 further comprises providing a light detection deviceconnected to the SIC.
 14. The method as in claim 9 further comprisingproviding a tinned wire disposed between the line wire shield and theinsulated line wire.
 15. The method as in claim 9 further comprising:providing a mechanically latched double pole switch disposed between theAC line end and the load end; providing a solenoid for delatching themechanically latched double pole switch upon a delatching signal fromthe LCDC or SIC.
 16. The method as in claim 9 further comprisesproviding an immersion detection cable between the load end and the ACline end of the power cord.
 17. The method as in claim 11 whereinproviding the power supply circuit further comprises providing a fullwave bridge rectifier circuit.
 18. A method for interrupting AC linevoltage between an alternating current (AC) line end and a load end of ashielded power cord upon detection of a power cord fault, the methodcomprising: providing a leakage current detection circuit (LCDC) fordetecting AC leakage current from the power cord and interrupting linevoltage between the AC line end and the load end of the shielded powercord if leakage current is detected, wherein providing the LCDC furthercomprises: providing a hi-stable latching device having an on/off state;providing a charge holding device connected to the bi-stable latchingdevice; charging the charge holding device to a first charge; providinga shield integrity circuit (SIC) for monitoring shielded power cordintegrity and interrupting line voltage between the AC line end and theload end of the shielded power cord if shield integrity is compromised;connecting the LCDC and SIC to the shielded power cord; providing apower supply circuit (PSC) for energizing the LCDC, SIC, and theshielded power cord with a first voltage; and energizing the shieldedpower cord with the first voltage.
 19. The method as in claim 18 whereinproviding a leakage current detection circuit (LCDC) for detectingleakage current from the shielded power cord further comprises latchingthe hi-stable latching device to an on-state and interrupting AC linevoltage between the load end and the line end of the shielded power cordif the first charge rises to a predetermined charge level.
 20. Themethod as in claim 18 wherein providing the shield integrity circuit(SIC) for monitoring the monitoring shielded power cord integrityfurther comprises: interrupting AC line voltage between the load end andthe AC line end of the power cord if the first voltage falls below afirst predetermined level.
 21. The method as in claim 20 whereinproviding the shield integrity circuit (SIC) further comprises:providing a first npn transistor; providing a solid-state switchingdevice; connecting the first npn transistor and the solid-stateswitching device to the power supply; connecting the first npntransistor collector to the solid-state switching device; sufficientlybiasing the first npn transistor to a conducting state to prevent thesolid-state switching device from switching from an off-condition to anon-condition in the absence of a power cord fault during a positivecycle of the AC line voltage; and biasing the first npn transistor to anon-conducting state to trigger the solid-state switching device to anon-state if a power cord fault is detected.
 22. The method as in claim21 wherein providing a solid-state switching device further comprisesproviding a second npn transistor.
 23. The method as in claim 21 whereinproviding a solid-state switching device further comprises providing asilicon-controlled rectifier (SCR).